An experimental device and method for simulating overflow and leakage coexisting well killing process of fracture-vug type formation

Abstract

The present application belongs to the technical field of oil and gas well drilling, and particularly relates to an experimental device and method for simulating overflow and leakage coexisting well killing process of fracture-cave type stratum. The device comprises a simulated wellbore system, a simulated drilling fluid circulation system, a simulated fracture-cave type stratum structure system, a simulated gas injection system, a data acquisition system and a data processing system. The simulated wellbore system is used for simulating the drill string and the wellbore in the experiment. The simulated drilling fluid circulation system is connected with the upper part of the wellbore system and is used for simulating the injection and return of the drilling fluid. The simulated fracture-cave type stratum structure system is connected with the lower part of the wellbore system and is used for simulating the fractures and the caves in the experiment. The simulated gas injection system is used for injecting gas into the fracture-cave type stratum structure system. The data acquisition system and the data processing system are used for collecting and processing the experimental data in the experimental device. The experimental device and method provided by the present application aim to solve the problem that the prior art cannot comprehensively simulate the overflow and leakage coexisting well killing process of the fracture-cave type stratum.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil and gas well drilling, and particularly relates to an experimental device and method for simulating overflow and leakage coexistence well killing process of fracture-cave type stratum. BACKGROUND

[0002] China's deep fracture-cave type carbonate rock oil and gas resources are abundant, with huge oil and gas resource potential, and have become an important target for China's oil and gas exploration and development and oil and gas reserve increase and production increase. Compared with permeable reservoirs, fracture-cave type carbonate rock reservoirs have good connectivity and strong pressure sensitivity, and the drilling fluid density window is narrow, so complex conditions such as overflow, leakage, and even overflow and leakage coexistence are prone to occur during drilling, and the well control risk is high, which can cause immeasurable losses to personnel safety, reservoirs, and production efficiency during drilling operation construction. At present, the well killing technology theory for solving overflow and leakage coexistence of fracture-cave type stratum is basically the field experience obtained by summarizing temporary technical measures after overflow and leakage occur in a specific fracture-cave type reservoir block, and has great limitations when used in other blocks.

[0003] During the overflow and leakage coexistence well killing process, the fluid flow state between the fracture-cave and the wellbore is mutually influenced, but there are few experimental methods for well killing process when overflow and leakage coexist in fracture-cave type stratum in China at present, and most experimental equipment is for studying the flow pressure in the wellbore or the evolution characteristics of the displacement interface in the fracture when gravity displacement occurs. The following is the technical background information related to the present application:

[0004] The patent "Wellbore fracture simulation device" (CN102305045A) simulates the drilling leakage process by connecting a fracture pipe to the simulated wellbore, without considering the specific conditions in the stratum.

[0005] The patent "Experimental device and method for simulating gas invasion into wellbore of fracture-cave type reservoir" (CN114737962A) connects several pipelines to simulate the wellbore and the simulated stratum, which is used to evaluate the gas flow characteristics during gas invasion of fracture-cave type stratum, but cannot simulate the stratum pressure control and the complex flow in the wellbore during overflow and leakage coexistence well killing process.

[0006] The patent "Experimental method for simulating well killing during overflow" (CN104835405A) uses the invention device to simulate the complex flow during drilling, simulates the driller method, engineer method or reverse circulation method well killing process under overflow conditions, but cannot simulate the well killing complex conditions when overflow and leakage coexist underground, and does not involve data collection and processing.

[0007] Therefore, the current research lacks consideration of the well killing process after overflow and leakage coexist and control of the formation pressure, and the laboratory experimental device and method lack relative comprehensive wellbore and fracture-cave type formation characteristics to consider the well killing process after overflow and leakage coexist. Therefore, it is of great significance to establish an experimental device and method for simulating the well killing process of overflow and leakage coexist in fracture-cave type formation, and study the pressure change characteristics of the wellbore and the formation during the well killing process of overflow and leakage coexist in fracture-cave type formation. SUMMARY

[0008] In order to solve the above problems in the prior art, that is, the prior art cannot comprehensively simulate the well killing process of overflow and leakage coexist in fracture-cave type formation, the present application provides an experimental device and method for simulating the well killing process of overflow and leakage coexist in fracture-cave type formation;

[0009] In the first aspect of the present application, an experimental device for simulating the well killing process of overflow and leakage coexist in fracture-cave type formation is provided, comprising: a simulated wellbore system, a simulated drilling fluid circulation system, a simulated fracture-cave type formation structure system, a simulated gas injection system, a data acquisition system and a data processing system.

[0010] The simulated wellbore system comprises a simulated wellbore and a simulated drill string.

[0011] The simulated drilling fluid circulation system comprises a liquid storage tank, a stirring motor, a drilling fluid centrifugal pump, a liquid injection control valve, a stirring motor, a gas-liquid separation tank and an overflow valve.

[0012] The simulated fracture-cave type formation structure system comprises a simulated fracture subsystem and a simulated cave subsystem; the simulated fracture subsystem comprises a first simulated fracture, a second simulated fracture, a first pneumatic ball valve and a second pneumatic ball valve; and the simulated cave subsystem comprises a simulated cave.

[0013] The simulated gas injection system comprises an air compressor, a gas storage tank, a gas injection control valve, a constant pressure check valve and a drilling fluid recovery tank.

[0014] The data acquisition system comprises a drilling fluid flowmeter, a return and output flowmeter, a standpipe pressure sensor, a casing pressure sensor, a bottom hole pressure sensor, a first simulated fracture pressure sensor, a second simulated fracture pressure sensor, a simulated cave pressure sensor, a gas flowmeter, a gas storage tank pressure sensor and a high-speed camera.

[0015] The data processing system comprises a data processor.

[0016] The simulated gas injection system is sequentially connected with the simulated fracture-vug type formation structure system, the simulated wellbore system and the simulated drilling fluid circulation system; the data acquisition system acquires parameters of the simulated wellbore system, parameters of the simulated drilling fluid circulation system, parameters of the simulated fracture-vug type formation structure system and parameters of the simulated gas injection system and uploads them to the data processing system.

[0017] In some preferred embodiments, the simulated gas injection system specifically comprises:

[0018] The output end of the air compressor is connected with the input end of the gas storage tank through a gas phase flow pipeline;

[0019] The output end of the gas storage tank is connected with the input end of the upper part of the simulated cave through a gas phase flow pipeline via a gas injection control valve; a gas flow meter is arranged in the gas phase flow pipeline between the input end of the simulated cave and the gas injection control valve, and a gas storage tank pressure sensor is arranged in the gas storage tank;

[0020] The lower part of the simulated cave is connected with the drilling fluid recovery tank through a gas phase flow pipeline via a constant pressure one-way valve.

[0021] In some preferred embodiments, the simulated fracture-vug type formation structure system specifically comprises:

[0022] The upper part of the simulated cave is connected with the simulated wellbore through a first simulated fracture and a first pneumatic ball valve; a first simulated fracture pressure sensor is arranged between the simulated wellbore and the first pneumatic ball valve;

[0023] The lower part of the simulated cave is connected with the simulated wellbore through a second simulated fracture and a second pneumatic ball valve; a second simulated fracture pressure sensor is arranged between the simulated wellbore and the second pneumatic ball valve.

[0024] In some preferred embodiments, the simulated wellbore system specifically comprises:

[0025] The simulated wellbore is vertically placed, the simulated drill string is vertically placed at the center of the simulated wellbore, and the upper end of the simulated drill string is higher than the simulated wellbore;

[0026] The upper end of the simulated wellbore is connected with the gas-liquid separation tank through a first flow pipeline via a return flow meter, and an overflow valve is arranged between the return flow meter and the simulated wellbore; the lower part of the simulated wellbore is connected with the first simulated fracture and the second simulated fracture respectively, and the connection positions of the first simulated fracture and the second simulated fracture with the simulated wellbore have a set height difference;

[0027] The upper part of the simulated wellbore is connected with a casing pressure sensor, the bottom of the simulated wellbore is provided with a bottom hole pressure sensor, and the top of the simulated drill string is connected with a stand pressure sensor.

[0028] In some preferred embodiments, the simulated drilling fluid circulation system specifically comprises:

[0029] The upper end of the simulated wellbore is connected to the first end of the gas-liquid separation tank through a gas-liquid two-phase pipeline;

[0030] The second end of the gas-liquid separation tank is extended above the liquid storage pool through a gas-liquid two-phase pipeline;

[0031] A stirring motor is arranged in the liquid storage pool, and the liquid storage pool is connected to the drilling fluid centrifugal pump through a pipeline;

[0032] The drilling fluid centrifugal pump is connected to the top end of the simulated drill string through a pipeline, and a drilling fluid flowmeter is arranged between the injection control valve and the simulated drill string.

[0033] In some preferred embodiments, the wellbore, the simulated fracture and the simulated cave are made of transparent organic glass, and the maximum bearing capacity is 1 MPa.

[0034] Another aspect of the present application is an experimental method for simulating the overflow and leakage coexistence well process of the fracture-cave type formation based on the experimental device for simulating the overflow and leakage coexistence well process of the fracture-cave type formation.

[0035] Step S100, connecting the device for simulating the overflow and leakage coexistence well process of the fracture-cave type formation, closing the injection control valve, the overflow valve, the first pneumatic ball valve, the second pneumatic ball valve, the gas injection control valve and the constant pressure check valve, and confirming the sealing property of the device;

[0036] Step S200, after adding clean water and weighting agent into the liquid storage pool, mixing the clean water and the weighting agent uniformly by the stirring motor to obtain simulated drilling fluid, and measuring the first simulated drilling fluid density;

[0037] Step S300, the air compressor is used to make the gas storage tank reach the set gas storage tank pressure;

[0038] Step S400, opening the gas injection control valve to inject compressed air from the gas storage tank into the simulated cave;

[0039] Step S500, opening the injection control valve and the overflow valve, and pumping the simulated drilling fluid in the liquid storage pool into the simulated drill string by the drilling fluid centrifugal pump;

[0040] The used simulated drilling fluid in the simulated drill string is returned to the gas-liquid separation tank through the simulated wellbore and the overflow valve;

[0041] The gas-liquid separation tank separates the used simulated drilling fluid into gas and liquid, and injects the separated simulated drilling fluid into the liquid storage pool;

[0042] Step S600, collecting sensor data through the drilling fluid flow meter, the return flow meter, the standpipe pressure sensor, the casing pressure sensor, the bottom hole pressure sensor, the first simulated fracture pressure sensor, the second simulated fracture pressure sensor, the simulated cave pressure sensor, the gas flow meter, the gas tank pressure sensor and the high-speed camera, and transmitting the sensor data to the data processor;

[0043] Step S700, when the first simulated fracture pressure sensor and the second simulated fracture pressure sensor data fluctuation range is less than the preset first stability threshold, based on the pressure difference between the simulated wellbore bottom hole pressure and the simulated cave, the coexistence condition of loss in the lower part of the simulated fracture-cave and overflow in the upper part of the simulated fracture-cave is controlled by adjusting the first pneumatic ball valve and the second pneumatic ball valve;

[0044] The real-time simulated standpipe pressure is obtained through the standpipe pressure sensor;

[0045] The real-time simulated wellhead pressure is obtained through the casing pressure sensor;

[0046] Step S800, when the instantaneous pressure of the simulated wellhead pressure reaches the set determination value, the second sensor data of the standpipe pressure sensor 9, the casing pressure sensor 10, the bottom hole pressure sensor 12, the simulated cave pressure sensor 20 and the high-speed camera 28 are read, and the first simulated standpipe pressure, the first simulated wellhead pressure, the first simulated cave pressure and the first gas-liquid two-phase distribution are recorded;

[0047] Step S900, the drilling fluid centrifugal pump 2 and the overflow valve 30 are closed, when the real-time simulated wellhead pressure fluctuation range is less than the preset second stability threshold within the preset time period, the simulated standpipe pressure at this time is recorded as the stable standpipe pressure, the simulated wellhead pressure at this time is recorded as the stable wellhead pressure, the second simulated drilling fluid density required for drilling is calculated, and the simulated drilling fluid in the liquid pool 1 is adjusted to the second simulated drilling fluid density;

[0048] The second simulated drilling fluid density ρ k , and the calculation method is:

[0049]

[0050] P p represents the stable standpipe pressure, h l represents the simulated wellbore height, ρ l represents the simulated drilling fluid density in the previous round of experiment; when n = 1, ρ l represents the first simulated drilling fluid density.

[0051] Step S1000, open the drilling fluid centrifugal pump to the set displacement, adjust the overflow valve to the set opening, make the real-time simulated wellhead pressure reach the stable wellhead pressure, simulate the current well killing method process, read the third sensor data of the standpipe pressure sensor, casing pressure sensor, bottom hole pressure sensor, simulated cave pressure sensor and high-speed camera, record the second simulated standpipe pressure, second simulated wellhead pressure, second simulated cave pressure and second gas-liquid two-phase distribution;

[0052] Step S1100, based on the first simulated standpipe pressure, first simulated wellhead pressure, first simulated cave pressure, first gas-liquid two-phase distribution, second simulated standpipe pressure, second simulated wellhead pressure, second simulated cave pressure and second gas-liquid two-phase distribution, calculate the simulated wellhead pressure change, simulated cave pressure change and gas-liquid flow rule, complete the n-th round of simulated fractured-vuggy formation condition experiment to obtain the n-th round of experimental results;

[0053] Step S1200, select a new simulated drilling fluid density, set displacement, and one or more well killing methods, let n=n+1, return to step S700.

[0054] In some preferred embodiments, after opening the gas injection control valve and injecting compressed air from the gas storage tank into the simulated cave, the pressure difference between the simulated wellbore and the simulated cave is set, the constant pressure overflow valve is opened, and the pressure in the simulated cave is maintained at the preset simulated cave pressure, and the simulated well killing process of overflow and loss coexistence under constant formation pressure in the fractured-vuggy formation is carried out.

[0055] In some preferred embodiments, after opening the gas injection control valve and injecting compressed air from the gas storage tank into the simulated cave, the simulated cave pressure is set, and when the pressure in the simulated cave reaches the preset simulated cave pressure, the gas injection control valve and the constant pressure overflow valve are closed, and the simulated well killing process of overflow and loss coexistence under constant fracture volume in the fractured-vuggy formation is carried out.

[0056] Advantages of the present application:

[0057] (1) The fractured-vuggy formation structure system of the present application includes two simulated fractures with a set height difference, which can realize the simulation of the downhole working condition of overflow and loss coexistence;

[0058] (2) The control of the drilling fluid circulation system and the gas injection system in the method of the present application can simulate the complex flow in the wellbore during the overflow and loss coexistence condition and the well killing process by adjusting the valve devices, and realize the experimental environment under the conditions of constant volume and constant pressure of the formation;

[0059] (3) The experimental device of the present application can realize the collection and processing of gas-liquid flow data in each system through various sensors, flow meters and high-speed cameras arranged in the system, combined with a data processing system. BRIEF DESCRIPTION OF DRAWINGS

[0060] Other features, objects, and advantages of the application will become more apparent from the following detailed description of non-limiting embodiments made with reference to the drawings:

[0061] Figure 1 A schematic structural diagram of an experimental device for simulating a process of overflow and leakage coexisting well killing in a fracture-vug type formation in an embodiment. DETAILED DESCRIPTION

[0062] The application will be further described in conjunction with the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related application, but not to limit the application. In addition, it should be noted that only the parts related to the application are shown in the drawings for ease of description.

[0063] It should be noted that the embodiments in the application and the features in the embodiments can be combined with each other without conflict.

[0064] An experimental device for simulating a process of overflow and leakage coexisting well killing in a fracture-vug type formation in a first embodiment of the application, a schematic structural diagram is shown in Figure 1 including a simulated wellbore system, a simulated drilling fluid circulation system, a simulated fracture-vug type formation structure system, a simulated gas injection system, a data acquisition system and a data processing system;

[0065] The simulated wellbore system includes a simulated wellbore 11 and a simulated drill string 7.

[0066] The simulated drilling fluid circulation system includes a liquid storage tank 1, a stirring motor 5, a drilling fluid centrifugal pump 2, a liquid injection control valve 3, a stirring motor 5, a gas-liquid separation tank 6 and an overflow valve 30.

[0067] The simulated fracture-vug type formation structure system includes a simulated fracture subsystem and a simulated cave subsystem; the simulated fracture subsystem includes a first simulated fracture 15, a second simulated fracture 18, a first pneumatic ball valve 14 and a second pneumatic ball valve 17; the simulated cave subsystem includes a simulated cave 19.

[0068] The simulated gas injection system includes an air compressor 25, a gas storage tank 24, a gas injection control valve 22, a constant pressure check valve 26 and a drilling fluid recovery tank 27.

[0069] The data acquisition system includes a drilling fluid flowmeter 4, a return and output flowmeter 8, a standpipe pressure sensor 9, a casing pressure sensor 10, a bottom hole pressure sensor 12, a first simulated fracture pressure sensor 13, a second simulated fracture pressure sensor 16, a simulated cave pressure sensor 20, a gas flowmeter 21, a gas storage tank pressure sensor 23 and a high-speed camera 28.

[0070] The data processing system comprises a data processor 28;

[0071] The simulated gas injection system is sequentially connected with the simulated fracture-vug type formation structure system, the simulated wellbore system and the simulated drilling fluid circulation system; the data acquisition system acquires parameters of the simulated wellbore system, the simulated drilling fluid circulation system, the simulated fracture-vug type formation structure system and the simulated gas injection system respectively and uploads them to the data processing system.

[0072] In the embodiment, the simulated gas injection system specifically comprises:

[0073] An output end of the air compressor 25 is connected with an input end of the gas storage tank 24 through a gas phase flow pipeline;

[0074] An output end of the gas storage tank 24 is connected with an input end of the upper part of the simulated cave 19 through a gas phase flow pipeline via the gas injection control valve 22; a gas flow meter 21 is arranged in the gas phase flow pipeline between the input end of the simulated cave 19 and the gas injection control valve 22, and a gas storage tank pressure sensor 23 is arranged in the gas storage tank 24;

[0075] The lower part of the simulated cave 19 is connected with the drilling fluid recovery tank 27 through a gas phase flow pipeline via the constant pressure one-way valve 26.

[0076] In the embodiment, the simulated fracture-vug type formation structure system specifically comprises:

[0077] The upper part of the simulated cave 19 is connected with the simulated wellbore 11 via the first simulated fracture 15 and the first pneumatic ball valve 14; a first simulated fracture pressure sensor 13 is arranged between the simulated wellbore and the first pneumatic ball valve 14;

[0078] The lower part of the simulated cave 19 is connected with the simulated wellbore 11 via the second simulated fracture 18 and the second pneumatic ball valve 17; a second simulated fracture pressure sensor 16 is arranged between the simulated wellbore and the second pneumatic ball valve 17.

[0079] In the embodiment, the simulated wellbore system specifically comprises:

[0080] The simulated wellbore 11 is vertically placed, the simulated drill string 7 is vertically placed in the center of the simulated wellbore 11, and the upper end of the simulated drill string 7 is higher than the simulated wellbore 11;

[0081] The upper end of the simulated wellbore 11 is connected with the gas-liquid separation tank 6 via the return flow meter 8 through a first flow pipeline, an overflow valve 30 is arranged between the return flow meter 8 and the simulated wellbore 11; the lower part of the simulated wellbore 11 is connected with the first simulated fracture 15 and the second simulated fracture 18 respectively, and the connection positions of the first simulated fracture 15 and the second simulated fracture 18 with the simulated wellbore 11 have a set height difference;

[0082] The upper part of the simulated wellbore 11 is connected with the casing pressure sensor 10, and the bottom of the simulated wellbore 11 is provided with the bottom hole pressure sensor 12.

[0083] In the embodiment, the simulated drilling fluid circulation system specifically comprises:

[0084] The upper end of the simulated wellbore 11 passes through the return flow meter 8 and is connected with the first end of the gas-liquid separation tank 6 through a gas-liquid two-phase pipeline;

[0085] The second end of the gas-liquid separation tank 6 extends above the liquid storage tank 1 through a gas-liquid two-phase pipeline;

[0086] The liquid storage tank 1 is provided with the stirring motor 5, and the liquid storage tank 1 is connected to the drilling fluid centrifugal pump 2 through a pipeline;

[0087] The drilling fluid centrifugal pump 2 is connected to the top end of the simulated drill string 7 through a pipeline and passes through the liquid injection control valve 3, and the drilling fluid flow meter 4 is arranged between the liquid injection control valve 3 and the simulated drill string 7.

[0088] In the embodiment, the wellbore 11, the simulated fracture 15, the simulated fracture 18 and the simulated solution cave 19 are made of transparent organic glass, and the maximum bearing pressure capacity is 1 MPa.

[0089] The experimental method for simulating the overflow and leakage coexistence pressure well process of the fracture-cave type formation according to the second embodiment of the present application uses the experimental device for simulating the overflow and leakage coexistence pressure well process of the fracture-cave type formation according to the first embodiment to carry out the simulated pressure well process of the overflow and leakage coexistence of the fracture-cave type formation under the condition of constant formation pressure, and comprises steps S100-S1200, and each step is described in detail as follows:

[0090] Step S100, connecting the device for simulating the overflow and leakage coexistence pressure well process of the fracture-cave type formation, closing the liquid injection control valve 3, the overflow valve 30, the first pneumatic ball valve 14, the second pneumatic ball valve 17, the gas injection control valve 22 and the constant pressure one-way valve 26, and confirming the sealing property of the device;

[0091] Step S200, after adding clean water and weighting agents into the liquid storage tank 1, the clean water and the weighting agents are uniformly mixed by the stirring motor 5 to obtain simulated drilling fluid, and the first simulated drilling fluid density is measured;

[0092] Step S300, the air storage tank 24 reaches the set air storage tank pressure by the air compressor 25;

[0093] Step S400, opening the gas injection control valve 22, injecting compressed air from the air storage tank 24 into the simulated solution cave 19, setting the pressure difference between the simulated wellbore 11 and the simulated solution cave 19, opening the constant pressure overflow valve 26, and keeping the pressure in the simulated solution cave 19 at the preset simulated solution cave pressure;

[0094] Step S500, open the injection control valve 3 and the overflow valve 30, and pump the simulated drilling fluid in the storage pool 1 into the simulated drill string 7 through the drilling fluid centrifugal pump 2;

[0095] The simulated drilling fluid in the simulated drill string 7 will be returned to the gas-liquid separation tank 6 through the simulated wellbore 11 and the overflow valve 30 after being used;

[0096] The gas-liquid separation tank 6 will separate the used simulated drilling fluid into gas and liquid, and inject the separated simulated drilling fluid into the storage pool;

[0097] Step S600, collect sensor data through the drilling fluid flow meter 4, the return flow meter 8, the standpipe pressure sensor 9, the casing pressure sensor 10, the bottom hole pressure sensor 12, the first simulated fracture pressure sensor 13, the second simulated fracture pressure sensor 16, the simulated cave pressure sensor 20, the gas flow meter 21, the gas storage tank pressure sensor 23, and the high-speed camera 28, and transmit the sensor data to the data processor 28;

[0098] Step S700, when the data fluctuation range of the first simulated fracture pressure sensor 13 and the second simulated fracture pressure sensor 16 is less than a preset first stability threshold, based on the pressure difference between the bottom hole pressure of the simulated wellbore 11 and the simulated cave 19, the coexistence condition of loss in the lower part of the simulated fracture-cave and overflow in the upper part of the simulated fracture-cave is controlled by adjusting the first pneumatic ball valve 14 and the second pneumatic ball valve 17;

[0099] The real-time simulated standpipe pressure is obtained through the standpipe pressure sensor 9;

[0100] The real-time simulated wellhead pressure is obtained through the casing pressure sensor 10;

[0101] Step S800, when the instantaneous pressure of the simulated wellhead pressure reaches a set determination value, the second sensor data of the standpipe pressure sensor 9, the casing pressure sensor 10, the bottom hole pressure sensor 12, the simulated cave pressure sensor 20, and the high-speed camera 28 are read, and the first simulated wellhead pressure, the first simulated wellhead pressure, the first simulated cave pressure, and the first gas-liquid two-phase distribution are recorded;

[0102] Step S900, close the drilling fluid centrifugal pump 2 and the overflow valve 30, and when the real-time simulated wellhead pressure fluctuates within a preset time period with a range less than a preset second stability threshold, the simulated standpipe pressure at this time is recorded as the stable standpipe pressure, the simulated wellhead pressure at this time is recorded as the stable wellhead pressure, the second simulated drilling fluid density required for drilling is calculated, and the simulated drilling fluid in the storage pool 1 is adjusted to the second simulated drilling fluid density;

[0103] The second simulated drilling fluid density ρ k , kg / cm 3 , and the calculation method is as follows:

[0104]

[0105] P p represents the stable riser pressure, h l represents the simulated wellbore height, ρ l represents the simulated drilling fluid density in the previous round of experiments; when n = 1, ρ l represents the first simulated drilling fluid density.

[0106] Step S1000, open the drilling fluid centrifugal pump 2 to a set displacement, adjust the overflow valve 30 to a set opening, make the real-time simulated wellhead pressure reach the stable wellhead pressure, simulate the current kill method process, read the third sensor data of the standpipe pressure sensor 9, the casing pressure sensor 10, the bottom hole pressure sensor 12, the simulated cave pressure sensor 20 and the high-speed camera 28, and record the second simulated standpipe pressure, the second simulated wellhead pressure, the second simulated cave pressure and the second gas-liquid two-phase distribution;

[0107] Step S1100, based on the first simulated standpipe pressure, the first simulated wellhead pressure, the first simulated cave pressure, the first gas-liquid two-phase distribution, the second simulated standpipe pressure, the second simulated wellhead pressure, the second simulated cave pressure and the second gas-liquid two-phase distribution, calculate the simulated wellhead pressure change, the simulated cave pressure change and the gas-liquid flow rule, complete the n-th round of simulated fractured-vuggy formation condition experiment to obtain the n-th round of experimental results;

[0108] Step S1200, select one or more of a new simulated drilling fluid density, a set displacement, and a kill method, let n = n + 1, and return to step S700.

[0109] The third embodiment of the application is an experimental method for simulating the overflow and leakage coexistence kill process of the fractured-vuggy formation, which uses the experimental device for simulating the overflow and leakage coexistence kill process of the fractured-vuggy formation in the first embodiment to carry out the simulated kill process of the overflow and leakage coexistence under the constant fractured-vuggy volume condition of the fractured-vuggy formation, and includes steps S100-S1200, which are described in detail as follows:

[0110] Step S100, connect the device for simulating the overflow and leakage coexistence kill process of the fractured-vuggy formation, close the liquid injection control valve 3, the overflow valve 30, the first pneumatic ball valve 14, the second pneumatic ball valve 17, the gas injection control valve 22 and the constant pressure check valve 26, and confirm the sealing property of the device;

[0111] Step S200, after adding clean water and weighting agents into the liquid storage tank 1, mix the clean water and the weighting agents uniformly through the stirring motor 5 to obtain the simulated drilling fluid, and measure the first simulated drilling fluid density;

[0112] Step S300, the air tank 24 reaches the set air tank pressure by the air compressor 25;

[0113] Step S400, open the gas injection control valve 22, make the air tank 24 inject compressed air into the simulated cave 19; set the simulated cave pressure, when the pressure in the simulated cave 19 reaches the preset simulated cave pressure, close the gas injection control valve 22 and the constant pressure overflow valve 26;

[0114] Step S500, open the liquid injection control valve 3 and the overflow valve 30, and pump the simulated drilling fluid in the liquid pool 1 into the simulated drill string 7 through the drilling fluid centrifugal pump 2;

[0115] The simulated drilling fluid in the simulated drill string 7, the used simulated drilling fluid is returned to the gas-liquid separation tank 6 through the simulated wellbore 11 and the overflow valve 30;

[0116] The gas-liquid separation tank 6 carries out gas-liquid separation on the used simulated drilling fluid, and injects the separated simulated drilling fluid into the liquid pool;

[0117] Step S600, collect sensor data through the drilling fluid flow meter 4, the return flow meter 8, the stand pressure sensor 9, the casing pressure sensor 10, the bottom hole pressure sensor 12, the first simulated fracture pressure sensor 13, the second simulated fracture pressure sensor 16, the simulated cave pressure sensor 20, the gas flow meter 21, the air tank pressure sensor 23 and the high-speed camera 28, and transmit the sensor data to the data processor 28;

[0118] Step S700, when the first simulated fracture pressure sensor 13 and the second simulated fracture pressure sensor 16 data fluctuation range is less than the preset first stable threshold, based on the pressure difference between the simulated wellbore 11 bottom hole pressure and the simulated cave 19, by adjusting the first pneumatic ball valve 14 and the second pneumatic ball valve 17 control the same condition of loss in the lower part of the simulated fracture-cave and overflow in the upper part of the fracture-cave;

[0119] Obtain the real-time simulated standpipe pressure through the stand pressure sensor 9;

[0120] Obtain the real-time simulated wellhead pressure through the casing pressure sensor 10;

[0121] Step S800, when the instantaneous pressure of the simulated wellhead pressure reaches the set determination value, read the second sensor data of the stand pressure sensor 9, the casing pressure sensor 10, the bottom hole pressure sensor 12, the simulated cave pressure sensor 20 and the high-speed camera 28, record the first simulated wellhead pressure, the first simulated wellhead pressure, the first simulated cave pressure and the first gas-liquid two-phase distribution;

[0122] Step S900, close the drilling fluid centrifugal pump 2 and the overflow valve 30, when the real-time simulated wellhead pressure fluctuation range is less than the preset second stability threshold within the preset time period, record the simulated standpipe pressure at this time as the stable standpipe pressure, record the simulated wellhead pressure at this time as the stable wellhead pressure, calculate the second simulated drilling fluid density required for drilling, and adjust the simulated drilling fluid in the liquid storage tank 1 to the second simulated drilling fluid density;

[0123] The second simulated drilling fluid density ρ k The calculation method is:

[0124]

[0125] P p The stable standpipe pressure is represented by h l The simulated wellbore height is represented by ρ l The simulated drilling fluid density in the previous round of experiments is represented by ρ l The first simulated drilling fluid density is represented by ρ

[0126] Step S1000, open the drilling fluid centrifugal pump 2 to the set displacement, adjust the overflow valve 30 to the set opening, make the real-time simulated wellhead pressure reach the stable wellhead pressure, simulate the current kill method process, read the third sensor data of the standpipe pressure sensor 9, the casing pressure sensor 10, the bottom hole pressure sensor 12, the simulated cave pressure sensor 20 and the high-speed camera 28, record the second simulated standpipe pressure, the second simulated wellhead pressure, the second simulated cave pressure and the second gas-liquid two-phase distribution;

[0127] Step S1100, based on the first simulated standpipe pressure, the first simulated wellhead pressure, the first simulated cave pressure, the first gas-liquid two-phase distribution, the second simulated standpipe pressure, the second simulated wellhead pressure, the second simulated cave pressure and the second gas-liquid two-phase distribution, calculate the simulated wellhead pressure change, the simulated cave pressure change and the gas-liquid flow rule, complete the n-th round of simulated fractured-vuggy reservoir experiment to obtain the n-th round of experimental results;

[0128] Step S1200, select one or more of a new simulated drilling fluid density, a set displacement, and a kill method, set n=n+1, and return to step S700.

[0129] Although the above embodiment describes each step in the above order, those skilled in the art can understand that, in order to achieve the effect of the embodiment, the different steps do not have to be executed in such an order, they can be executed simultaneously (in parallel) or in a reversed order, and these simple changes are within the protection scope of the present application.

[0130] The terms "first", "second", and the like, are used to distinguish between similar objects, not to denote or imply a particular order or sequence.

[0131] The term "comprising" or any other similar term is intended to encompass the inclusion of non-exclusive elements, such that a process, method, article, or apparatus / device that comprises a list of elements does not necessarily include only those elements, but can include other elements not expressly listed or inherent to such process, method, article, or apparatus / device.

[0132] So far, the technical solutions of the present application have been described in combination with the preferred embodiments shown in the drawings, but it is easy for those skilled in the art to understand that the protection scope of the present application is obviously not limited to these specific embodiments. Those skilled in the art can make equivalent changes or replacements to the related technical features without departing from the principles of the present application, and the technical solutions after these changes or replacements will all fall within the protection scope of the present application.

Claims

1. An experimental device for simulating a well control process in a fractured-vug type formation with overflow and simultaneous circulation, characterized in that, The device comprises a simulated wellbore system, a simulated drilling fluid circulation system, a simulated fracture-cave type formation structure system, a simulated gas injection system, a data acquisition system and a data processing system; The simulated wellbore system comprises a simulated wellbore (11) and a simulated drill string (7); The simulated drilling fluid circulation system comprises a liquid storage tank (1), a stirring motor (5), a drilling fluid centrifugal pump (2), a liquid injection control valve (3), a stirring motor (5), a gas-liquid separation tank (6) and an overflow valve (30); The simulated fracture-cave type formation structure system comprises a simulated fracture subsystem and a simulated cave subsystem; the simulated fracture subsystem comprises a first simulated fracture (15), a second simulated fracture (18), a first pneumatic ball valve (14) and a second pneumatic ball valve (17); and the simulated cave subsystem comprises a simulated cave (19); The simulated gas injection system comprises an air compressor (25), a gas storage tank (24), a gas injection control valve (22), a constant pressure check valve (26) and a drilling fluid recovery tank (27); The data acquisition system comprises a drilling fluid flowmeter (4), a return flowmeter (8), a standpipe pressure sensor (9), a casing pressure sensor (10), a bottom hole pressure sensor (12), a first simulated fracture pressure sensor (13), a second simulated fracture pressure sensor (16), a simulated cave pressure sensor (20), a gas flowmeter (21), a gas storage tank pressure sensor (23) and a high-speed camera (28); The data processing system comprises a data processor (29); The simulated gas injection system is sequentially connected to the simulated fracture-cave type formation structure system, the simulated wellbore system and the simulated drilling fluid circulation system; the data acquisition system acquires parameters of the simulated wellbore system, the simulated drilling fluid circulation system, the simulated fracture-cave type formation structure system and the simulated gas injection system and uploads them to the data processing system; An output end of the air compressor (25) is connected to an input end of the gas storage tank (24) through a gas phase flow pipeline; An output end of the gas storage tank (24) is connected to an input end of an upper portion of the simulated cave (19) through a gas phase flow pipeline via the gas injection control valve (22); a gas flowmeter (21) is arranged in the gas phase flow pipeline between the input end of the simulated cave (19) and the gas injection control valve (22), and a gas storage tank pressure sensor (23) is arranged in the gas storage tank (24); A lower portion of the simulated cave (19) is connected to the drilling fluid recovery tank (27) through a gas phase flow pipeline via the constant pressure check valve (26); The upper portion of the simulated cave (19) is connected to the simulated wellbore (11) via the first simulated fracture (15) and the first pneumatic ball valve (14); a first simulated fracture pressure sensor (13) is arranged between the simulated wellbore and the first pneumatic ball valve (14); The lower portion of the simulated cave (19) is connected to the simulated wellbore (11) via the second simulated fracture (18) and the second pneumatic ball valve (17); a second simulated fracture pressure sensor (16) is arranged between the simulated wellbore and the second pneumatic ball valve (17). The simulated wellbore (11) is vertically placed, and the simulated drill string (7) is vertically placed at the center of the simulated wellbore (11), and the upper end of the simulated drill string (7) is higher than the simulated wellbore (11); The upper end of the simulated wellbore (11) is connected to the gas-liquid separation tank (6) through the return flow meter (8) through the first flow pipe, and the overflow valve (30) is arranged between the return flow meter (8) and the simulated wellbore (11); The lower part of the simulated wellbore (11) is connected with the first simulated fracture (15) and the second simulated fracture (18) respectively, and the connection positions of the first simulated fracture (15) and the second simulated fracture (18) with the simulated wellbore (11) have a set height difference; The upper part of the simulated wellbore (11) is connected with the casing pressure sensor (10), and the bottom of the simulated wellbore (11) is provided with the bottom hole pressure sensor (12), and the top of the simulated drill string (7) is connected with the stand pressure sensor (9); The upper end of the simulated wellbore (11) passes through the return flow meter (8) and is connected with the first end of the gas-liquid separation tank (6) through the gas-liquid two-phase pipe; The second end of the gas-liquid separation tank (6) extends above the liquid storage tank (1) through the gas-liquid two-phase pipe; The stirring motor (5) is arranged in the liquid storage tank (1); The liquid storage tank (1) is connected to the drilling fluid centrifugal pump (2) through the pipe; The drilling fluid centrifugal pump (2) is connected to the top end of the simulated drill string (7) through the pipe through the liquid injection control valve (3); wherein the drilling fluid flow meter (4) is arranged between the liquid injection control valve (3) and the simulated drill string (7).

2. An experimental method for simulating a well control process of a thief zone in a fractured-vug type formation, characterized in that, The method is based on the experimental device for simulating the overflow and leakage coexistence well process of the fracture-cave type formation of claim 1, and the method comprises: Step S100, connecting the device for simulating the overflow and leakage coexistence well process of the fracture-cave type formation, closing the liquid injection control valve (3), the overflow valve (30), the first pneumatic ball valve (14), the second pneumatic ball valve (17), the gas injection control valve (22) and the constant pressure one-way valve (26), and confirming the sealing property of the device; Step S200, after adding clean water and weighting agent into the liquid storage tank (1), mixing the clean water and the weighting agent uniformly by the stirring motor (5) to obtain the simulated drilling fluid, and measuring the first simulated drilling fluid density; Step S300, the air storage tank (24) reaches the set air storage tank pressure by the air compressor (25); Step S400, opening the gas injection control valve (22) to inject compressed air from the air storage tank (24) into the simulated cave (19); Step S500, opening the liquid injection control valve (3) and the overflow valve (30), and pumping the simulated drilling fluid in the liquid storage tank (1) into the simulated drill string (7) by the drilling fluid centrifugal pump (2); The simulated drilling fluid in the simulated drill string (7) is returned to the gas-liquid separation tank (6) through the simulated wellbore (11) and the overflow valve (30); The gas-liquid separation tank (6) separates the used simulated drilling fluid, and injects the separated simulated drilling fluid into the liquid storage tank; Step S600, sensor data is collected through the drilling fluid flowmeter (4), the flowback flowmeter (8), the standpipe pressure sensor (9), the casing pressure sensor (10), the bottom hole pressure sensor (12), the first simulated fracture pressure sensor (13), the second simulated fracture pressure sensor (16), the simulated cave pressure sensor (20), the gas flowmeter (21), the gas storage tank pressure sensor (23), and the high-speed camera (28), and the sensor data is transmitted to the data processor (29); Step S700, when the first simulated fracture pressure sensor (13) and the second simulated fracture pressure sensor (16) data fluctuation range is less than the first preset stable threshold, based on the pressure difference between the simulated wellbore (11) bottom hole pressure and the simulated cave (19), the first pneumatic ball valve (14) and the second pneumatic ball valve (17) are adjusted to control the coexistence of loss in the lower part of the simulated fracture-cave and overflow in the upper part of the fracture-cave; The real-time simulated standpipe pressure is obtained through the standpipe pressure sensor (9); The real-time simulated wellhead pressure is obtained through the casing pressure sensor (10); Step S800, when the instantaneous pressure of the simulated wellhead pressure reaches the set determination value, the second sensor data of the standpipe pressure sensor (9), the casing pressure sensor (10), the bottom hole pressure sensor (12), the simulated cave pressure sensor (20), and the high-speed camera (28) is read, and the first simulated standpipe pressure, the first simulated wellhead pressure, the first simulated cave pressure, and the first gas-liquid two-phase distribution are recorded; Step S900, the drilling fluid centrifugal pump (2) and the overflow valve (30) are closed, when the real-time simulated wellhead pressure fluctuation range is less than the second preset stable threshold within a preset time period, the simulated standpipe pressure at this time is recorded as the stable standpipe pressure, the simulated wellhead pressure at this time is recorded as the stable wellhead pressure, the second simulated drilling fluid density required for drilling is calculated, and the simulated drilling fluid in the liquid storage tank (1) is adjusted to the second simulated drilling fluid density; Step S1000, the drilling fluid centrifugal pump (2) is opened to a set displacement, the overflow valve (30) is adjusted to a set opening, the real-time simulated wellhead pressure reaches the stable wellhead pressure, the current well killing method process is simulated, the third sensor data of the standpipe pressure sensor (9), the casing pressure sensor (10), the bottom hole pressure sensor (12), the simulated cave pressure sensor (20), and the high-speed camera (28) is read, and the second simulated standpipe pressure, the second simulated wellhead pressure, the second simulated cave pressure, and the second gas-liquid two-phase distribution are recorded; Step S1100, based on the first simulated standpipe pressure, the first simulated wellhead pressure, the first simulated cave pressure, the first gas-liquid two-phase distribution, the second simulated standpipe pressure, the second simulated wellhead pressure, the second simulated cave pressure, and the second gas-liquid two-phase distribution, the simulated wellhead pressure change, the simulated cave pressure change, and the gas-liquid flow rule are calculated, and the nth round of simulated fracture-cave formation condition experiment is completed to obtain the nth round of experimental results; Step S1200, one or more of the new simulated drilling fluid density, the set displacement, and the well killing method are selected, n=n+1, and the step S700 is returned to.

3. The experimental method of simulating the overflow and underflow coexistence process of the interstitial type formation according to claim 2, characterized in that, After the opening of the gas injection control valve (22) to inject compressed air from the gas storage tank (24) into the simulated cave (19), the method further comprises the step of setting the pressure in the simulated cave (19), specifically comprising: Setting the pressure difference between the simulated wellbore (11) and the simulated cave (19), opening the constant pressure one-way valve (26), and keeping the pressure in the simulated cave (19) at the preset simulated cave pressure.

4. The experimental method of simulating the overflow and underflow coexistence well control process of the interpenetrated pore-fracture type formation according to claim 2, characterized in that, After the opening of the gas injection control valve (22) to inject compressed air from the gas storage tank (24) into the simulated cave (19), the method further comprises the step of setting the gas capacity in the simulated cave (19), specifically comprising: Setting the simulated cave pressure, and closing the gas injection control valve (22) and the constant pressure one-way valve (26) when the pressure in the simulated cave (19) reaches the preset simulated cave pressure.

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